Soitec stock plunges over 14%, worst performer on the SBF 120
The Isère-based semiconductor substrate manufacturer is recording the steepest decline on the SBF 120 index at mid-session, as the Paris market comes under broader pressure. The fall comes after a spectacular rally that began in early September, which had propelled the stock to extreme valuation levels.
Soitec drops to its 20-day moving average after a 14.45% intraday decline
The Soitec stock is down 14.45% to €120.75 during the session, bringing the share back to a level it has not visited for several weeks. The last close on Friday, September 11, stood at €141.15, which illustrates the scale of Monday's move. The stock is now trading near its 20-day moving average, set at €121.30, with a negative gap of only 0.45%: this threshold, which had supported the underlying bullish momentum, is now under threat. Below it, the 50-day moving average at €113.12 represents the next support level, approximately 6.3% further down.
Technical support at €104 is even further away, while resistance at €146.35 — tested unsuccessfully in early September, as preceding consolidation sessions had shown — is receding mechanically. The RSI at 63 remains in neutral-to-high territory, signaling that selling pressure does not yet indicate marked technical exhaustion: the stock is neither oversold nor overbought. Monthly volatility at 30%, already elevated, reflects the extremely turbulent nature of the stock since early September.
A stock returned to extreme valuation after a rally of nearly 290% over one year
Today's decline occurs in the context of an exceptional rally: Soitec was still posting a performance of nearly 289% over one year on Friday, driven by accelerating demand for Photonics-SOI substrates. On September 2, the company had raised its revenue growth forecast for the second quarter of fiscal year 2026-2027 to approximately 50%, triggering an upward sequence that had driven the stock to near its resistance level at €146.35. According to the consensus of analysts surveyed, the stock is trading at approximately 174 times current fiscal year earnings, and 37 times those of the following fiscal year: multiples that leave little room in case of disappointment or a shift in sentiment toward the semiconductor sector.
On Monday, the market backdrop is also weighing on technology and semiconductor stocks across Europe, in a session marked by investor nervousness surrounding the imminent monetary decisions from the Fed (Wednesday) and the Bank of Japan (Friday). The SBF 120 is down 0.9% at mid-session, but the magnitude of Soitec's decline far exceeds that of the index. At -5.89% over seven days and -12.09% over three months, the short-term momentum has clearly reversed, even though annual performance remains structurally very strong.
